Field of the Invention
The present invention relates to an image display device which forms an image using a light source and an optical modulator that modulates transmittance or reflectance of light incident from the light source per pixel according to a drive signal.
Description of the Related Art
Color matching functions that represent human visual characteristics related to color are known to have individual variability attributable to fluctuations caused by age and the like. CIE170-1 is proposed as a model of such a fluctuation by the CIE (International Commission on Illumination).
The existence of such individual variability sometimes causes color to be perceived on an image display device as being subtly different from person to person (hereinafter, referred to as “individual variability in color perception”). As a result, there may be cases where, depending on an observer, a color does not appear to be matched even after performing color calibration for colorimetric matching with printed matter. This phenomenon is particularly prominent among display devices using light sources with a narrow spectrum as a backlight in order to expand a display color gamut.
In order to solve this problem, there is a method of reducing individual variability in color perception by reproducing a color spectrum of the real world as faithfully as possible on the assumption that image signals and display devices have six primary colors (Japanese Patent Application Laid-open No. 2003-141518).
Alternatively, a display device is proposed which combines a broad light source having a broad emission spectrum and used in a display region of an image with low chroma and a narrow light source having a narrow emission spectrum and used in a display region of an image with high chroma and which selectively uses such combinations per region on a screen (Japanese Patent Application Laid-open No. 2012-515948). The display device is intended to achieve both a reduction of individual variability in color perception and an expansion of a display color gamut.
In addition, a method is proposed for forming an image with a substantially larger number of primary colors than the number of primary colors of pixels constituting an optical modulator by temporally dividing a display period of an image, and switching among and emitting light from a plurality of light sources with different emission colors in each subframe (Japanese Patent Application Laid-open No. 2004-138827).
Furthermore, a method is proposed for expanding a color gamut of a display device by changing an applied current value of an RGB basic light source per factice field to increase the number of colors of the light source (Japanese Patent Application Laid-open No. 2005-275204).